Control apparatus



Get. 24, 1967.

RESTRICTO H. D. OGREN CONTROL APPARATUS Filed Jan. 30, 1964 u I ANA, LOG 'AP=(FIH5) :]C

SIGNAL INPUT IGNAL TRANSDUCER AMPLIFIER INVENTOR. HARVEY D. OGREN AT TORNE Y United States Patent 3,348,562 CONTROL APPARATUS Harvey D. Ogren, Roseville, Miun., assignor to Honeywell Inc., a corporation of Delaware Filed Jan. 30, 1964, Ser. No. 341,235 11 Claims. (Cl. 137-815) This invention relates to fluid control devices and in particular concerns a variable frequency fluid oscillator.

The field of pure fluid devices utilizing no moving parts other than the working fluid employed therein is a relatively recent one. Being a relatively new field, the known technology is somewhat limited, especially in the restricted area of variable frequency sonic oscillators, In this restricted area the problem is one of varying the effective feedback passage length or cross-sectional" area of an oscillator without using moving parts. While the particular technique for obtaining variable oscillation frequency is novel, the individual elements in the system embodying the technique presently exist in the art.

Accordingly, it is an object of this invention to provide a variable frequency fluid oscillator having no moving parts.

It is another object of this invention to provide a variable frequency fluid oscillator where the composition of the working fluid is varied according to changes in pressure. It is another object to provide a variable frequency fluid oscillator having a feedback passage wherein the effective feedback passage length is varied by varying the composition of the'working fluid medium.

It is another object to provide a variable frequency fluid oscillator by varying the ratio of the specific heats of the working fluid medium.

Other objects and advantages of this invention will become apparent in the following description and in the drawing that shows the invention in plan view. The symbols used in the drawing conform to the general shapes of the various fluid elements as they exist in ,the art.

In describing the embodiment shown in the drawing, specific terminology will be used for the sake of cla rity. From this it should not be inferred that limitation by the specific terminology is intended and it is to be understood that each specific term includes all .technical equivalents that operate in a similar manner to accomplish a similar end. i

The drawing used in describing the invention includes a signal transducer 10, first and second biased fluid proportional amplifiers 12, 14, an air source 16, a helium source 18, fluid oscillators 20, 22, and a fluid proportional amplifier 24.

Signal transducer has analog signal input means 11 and develops a pressure differential signal across output orifices 26, 28 when an analog signal is applied to input means 11. The pressure and flow at orifice 26 are designated P F and the .same quantities at orifice 28 are designated P F The pressure differential will be designated AP, Where 18 are connected to inputs of the power nozzles 46, 48'

of amplifiers 12, 14. Amplifiers 12, 14 have jetinteraction chambers 50, 52. Adjacent chamber 50 are a pair of apertures 54, 56 and adjacent chamber 52 are a pair of apertures 58, 60.

The output signals of amplifiers 12, 14 are biased by the use of variable restrictors 62,65 in tubes 34, 36. Biasing is not strictly necessary, however, but depends upon the operating point selected. Assuming that AP=0 (i.e., P =P the pressure at nozzle 30 of amplifier 12 is less than the pressure P at nozzle 38 due to the pressure drop across restrictor 62. Since the fluid at nozzle 38 is at a greater pressure than the fluid at nozzle 30, a power jet composed of air under pressure issuing from the output orifice of nozzle 46 into chamber 50 is directed toward and into aperture 56. Aperture 56 is the input opening to tube 64, which transmits a fluid signal to input orifice 66 of power nozzle 68 in oscillator 20. In the same manner, when P :P the pressure of the fluid at nozzle 40 of amplifier 14, is greater than the pressure at nozzle 32 and a power jet composed of helium under pressure issuing from the output orifice of nozzle 48 into ehamber 52 is directed toward and into aperture 60 from where it is vented to the atmosphere through output tube 70. Notice that in this case no helium is directed toward aperture 58 and therefore output tube 72 connected to input orifice 74 of nozzle 68 in oscillator 20, delivers no helium to that nozzle.

Under these conditions a jet of air only issues from the output orifice of nozzle 68 into jet interaction chamber 76 of fluid oscillator 20. Oscillator 20' has a pair of apertures 78, 80 in chamber 76 that open into output tubes 82, 84. Branching off from output tubes 82, 84 are feedback passages 86, 88 that terminate in orifices 90, 92 opening into the chamber 76. Under certain conditions a signal fed from the output to the input of an amplifier causes oscillations. The frequency of the oscillation is dependent upon the length of the feedback passages 86, 88, the speed of sound, C, in the working fluid medium, in this case air, the time it takes for switching to occnr'in the interaction chamber 76, and possibly, the cross-sectional area of the feedback passages.

The input signal can be made to vary about zero, in which case the frequency of oscillation of the output will be the lowest when AP has the largest negative value.

Oscillator 22 is similar to oscillator 20. The input orifice of power nozzle 94 is connected to air source 16. The output orifice of nozzle 94 opens into interaction chamber 96 which in turn has a pair of apertures 98, 1.01) forming the input openings to outpu tubes 102, 1 04. Branching off from tubes 182, 104 are feedback passages 106, 108 which terminate in orifices 110, 112 also opening into chamber 96.

With both oscillators using the same working fluid medium (air) and with both oscillators having identical dimensions the frequencies of oscillation are equal.

Output tubes 82, 104 of oscillators 20, 22 are vented to the atmosphere but tubes 84, 102 terminate in orifices 114, 116 that open into interaction chamber 118 of amplifier 24. Amplifier 24 may be bistable or proportional. The input orifice of power nozzle 126 is connected to .air source 16, and the output orifice of nozzle 120 opens into jet interaction chamber 118 which in turn has a pair of apertures 122, 124. Apertures 122, 124 open into tubes 126, 128.

Amplifier 24 acts as a frequency mixer. The output signal frequency of amplifier 25 is a difference frequency f -f where f f are the frequencies of oscillators 20, 22, with f variable and f fixed. Frequency beating occurs in amplifier 24. The frequency f of oscillator 20 is variable because the composition of the working fluid medium is variable in that oscillator.

Up to this point it has been assumed that P=0.

Assume now that AP (P P When this condition occurs the pressure of the fluid nozzles 3t), 32 of amplifies 12, 14 increases. This causes a proportional part of the air power jet to be divertedinto apertures 54 and out the vented tube 136, and a proportional part of the helium power jet to be diverted to aperture 58 and through the tube 72 to nozzle 68 oscillator 20. From this it is seen that the composition of the working fluid medium used by oscillator 20 has been changed by subtracting air and adding helium. Since the velocity of sound, C, is greater in helium than in air, the effective length of the feedback passages 86, 88 has been decreased causing the frequency of oscillation, h, to increase. Although f has increased, f remains fixed, and an output frequency f f appears at the output of amplifier 24.

The oscillators 20, 22 are often referred to as sonic oscillators because they produce and utilize pressure waves that travel at the velocity of sound. The velocity of sound C varies according to the relation where P=pressure (dynes/cm y ratio of specific heats of the fluid working medium at constant pressure and at constant temperature, and

=density From Equation 2 it is evident that the velocity of sound, C, is independent of pressure or density provided that temperature is constant, since in accordance with Boyles law, P is proportional to p when the temperature is constant. Therefore, the ratio of the velocity of sound in helium to that in air is dependent only upon their specific heat ratios. By substituting the appropriate values for helium and air into Equation 2 it is found that the velocity of sound in helium is about 2.9 times faster than the velocity of sound in air. Accordingly, the maximum ratio of f /f =2.9 and the maximum difference f f The advantage of this apparatus are numerous. The apparatus is rugged and reliable because it has no moving parts. The apparatus will perform in an environment where electronic equipment operation would cease due to radiation of various types.

It is to be understood that the form of the invention herewith shown and described is to be taken as but one embodiment. Various changes may be made in the shape and arnangement of components. Equivalent elements may be substituted for those illustrated. Although two particular fluids are referred to in the description, limitation thereto is not to be implied. Certain features of the invention may be used independently of other features all without departing from the spirit or scope of the invention as defined in the appended claims.

I claim as my invention: a

1. A variable frequency pure fluid oscillator comprising, in combination:

a first proportional fluid amplifier having power input,

control input, and output means;

.a source of air, under pressure, connected to the power input means of the first amplifier;

a second proportional fluid amplifier having power input, control input, and output means;

a source of helium, under pressure, connected to the power input means of the second amplifier;

a first fluid oscillator having input and output means, the input means being connected to the output means of the first and second amplifiers;

a second fluid oscillator having output means and input means, the input means being connected to the air source;

a third fluid amplifier having power input means connected to the air source and first and second control means connected to the output means of the first and second oscillators; and,

a transducer, for developing a pressure diflerential corresponding to an analog signal, connected to the control input means of the first and second amplifiers to proportionally decrease the output of the first amplifier and proportionally increase the output of the second amplifier as the pressure differential increases.

2. The combination according to claim 1 wherein means for biasing the first and second amplifier are provided.

3. A variable frequency pure fluid oscillator comprising, in combination:

a first proportional fluid amplifier having power input,

control input, and output means;

a source of first fluid, under pressure, connected to the power input means of the first amplifier;

a second proportional fluid amplifier having power input, control input, and output means;

a source of second fluid, under pressure, connected to the power input means of the second amplifier;

a first fluid oscillator having input and output means, the input means being connected to the output means of the first and second amplifiers;

a second fluid oscillator having input means and output means, the input means being connected to the first fluid source;

a third fluid amplifier having power input means connected to the first fluid source and first and second control input means connected to the output means of the first and second oscillators; and,

a transducer, for developing a pressure differential signal corresponding to an analog signal, connected to the control input means of the first and second amplifiers to proportionally decrease the output of the first amplifier and proportionally increase the output of the second amplifier as the pressure differential increases.

4. A variable frequency pure fluid oscillator comprising, in combination:

a first proportional fluid amplifier having power input,

control input, and output means;

a source of first fluid, under pressure, connected to the power input means of the first amplifier;

a second proportional fluid amplifier having power input, control input, and output means;

a source of second fluid, under pressure, connected to the power input means of the second amplifier;

a first fluid oscillator having input and output means, the input means being connected to the output means of the first and second amplifier;

a second fluid oscillator having input means and output means, the input means being connected to the first fluid source;

a third proportional fluid amplifier having power input means connected to the first fluid source, and first and second control input means connected to the output means of the first and second oscillators; and

a transducer, for developing a pressure differential corresponding to an analog signal, connected to the control input means of the first and second amplifiers to proportionally decrease the output of the first amplifier and proportionally increase the output of the second amplifier as the pressure diflerential increases.

5. A variable frequency pure fluid oscillator comprising, in combination:

a first proportional fluid amplifier having power input,

control input, and output means;

a source of first fluid, under pressure, connected to the power input means of the first amplifier;

a second proportional fluid amplifier having power input, control input, and output means;

a source of second fluid, under pressure, connected to the power input means of the second amplifier, said second fluid having a diflerent propagation velocity for sound from that of said first fluid;

a fluid oscillator having input and output means, the input means being connected to the output means of first and second amplifiers; and

a transducer, for developing a pressure differential corresponding to an analog signal, connected tothe control input means of the first and second amplifiers to proportionally decrease the output of the first amplifier and proportionally increase the output of the second amplifier as the pressure differential increases.

6. A variable frequency pure fluid oscillator comprising, in combination:

a pair of proportional amplifiers, each having output means;

means supplying different working fluids to said amplifiers, said fluids having different propagation velocities for sound;

pressure differential responsive means;

means connecting said responsive means to said amplifiers, so that an increasing pressure differential causes one amplifier to have a proportionally decreasing output and causes the other amplifier to have a proportionally increasing output; and

a fluid oscillator having input means;

means connecting said output means to said input means to supply to said oscillator a working fluid medium that results from combining the outputs of the amplifier pair.

7. A variable frequency pure fluid oscillator comprising, in combination:

a source of pressure differential;

a pair of proportional fluid amplifiers, including output means;

means controlled by said pressure differential for supplying to said fluid amplifiers a pair of different working fluids having different propagation velocities for sound, whereby an increasing differential causes one amplifier to have a proportionally decreasing output and causes the other amplifier to have a proportionally increasing output; and

fluid oscillator means having input means connected to the output means of said amplifiers so that said oscillator is supplied with a working fluid medium that results from combining the outputs of the amplifier pair.

8. A variable frequency fluid oscillator comprising:

a first fluid oscillator having output means supplying a fixed fluid frequency output;

a second fluid oscillator, having output means supplying a fluid output the frequency of which varies with the composition of the fluid supplied thereto;

a plurality of sources supplying fluids in which sound travels at different speeds;

variable means connected to said sources and to said second fluid oscillator to vary the composition of the fluid supplied to said second oscillator to cause the frequency of said second fluid oscillator to vary; and

fluid amplifier means having control input means connected to said output means of said first fluid oscillator and said second fluid oscillator so that the frequency of said fluid output signal from said fluid amplifier is the difference between the frequencies of said first and second fluid oscillators.

9. In combination, a fluid oscillator, a plurality of sources of different fluids in which sound travels at different speeds, means supplying fluids from said sources to power said oscillator, and means in the last named means for varying the proportions of said fluids supplied to said oscillator to vary the frequency of oscillation of said oscillator.

10. In combination: a first fluid oscillator giving an output of a first frequency;

a second fluid oscillator giving an output of a second,

variable frequency; a fluid amplifier having a pair of control orifices and a fluid power inlet; and

means connecting said control orifices to receive said outputs, so that said fluid amplifier gives a fluid signal having a component of a frequency equal to the difference between the frequency of said outputs.

11. A fluid modulator comprising, in combination:

a fluid amplifier having output means and a plurality of control ports;

fluid oscillator means supplying to one of said control ports an alternating fluid signal of a first frequency; and

second fluid oscillator means supplying to another of said control ports an alternating fluid signal of a second frequency, whereby there appears at said output means an alternating fluid signal having a component with a frequency equal to the difference between said first and second frequencies.

References Cited UNITED STATES PATENTS 3,030,979 4/1962 Reilly 13781.5 3,117,593 1/1964 Sowers 137-81.5X 3,122,039 2/ 1964 Sowers. 3,159,168 12/1964 Reader 137-815 3,182,686 5/1965 Zilberfarb 13781.5X 3,273,377 9/1966 Testerman et al. 7323.1

OTHER REFERENCES Fluid Logic Parity Checking, H. R. Grubb, I.B.M. Technical Disclosure Bulletin, vol. 6, No. 1, June 1963, pp. 27 and 28.

M. CARY NELSON, Primary Examiner.

BENJAMIN A. BORCHELT, Examiner.

S. SCOTT, V. R. PENDEGRASS, R. V. LOTTMANN,

Assistant Examiners. 

9. IN COMBINATION, A FLUID OSCILLATOR, A PLURALITY OF SOURCES OF DIFFERENT FLUIDS IN WHICH SOUND TRAVELS AT DIFFERENT SPEEDS, MEANS SUPPLYING FLUIDS FROM SAID SOURCES TO POWER SAID OSCILLATOR, AND MEANS IN THE LAST NAMED MEANS FOR VARYING THE PROPORTIONS OF SAID FLUIDS SUPPLIED TO SAID OSCILLATOR TO VARY THE FREQUENCY OF OSCILLATION OF SAID OSCILLATOR. 